The present invention relates to heat engines and, more particularly, to a dual working fluid engine with improved thermal efficiency and throughput.
U.S. patent application Ser. No. 534,479 entitled "Parallel-Compound Dual Fluid Heat Engine" referenced above describes a heat engine, which is referred to herein as a dual fluid or Cheng cycle engine, which makes use of two separate working fluids. Each fluid is compressed separately, but they are combined in a single mixture for expansion and heat regeneration. This cycle essentially combines a Brayton cycle and regenerative Rankine cycle system in parallel such that operational limitations of compression ratio in the Brayton cycle, upper temperature in the Rankine cycle, and waste heat rejection in both cycles are removed. Regeneration using the Rankine cycle working fluid is another, very important, feature of this cycle.
Gas turbine (Brayton cycle) and steam turbine (Rankine cycle) engines each have their own advantages and disadvantages. These are discussed at pp. 6-10 of the patent application referred to above and are incorporated herein by reference.
The dual fluid engine at first glance has similarities with the combined cycle, regenerative gas turbine cycles, and water injected gas turbine cycles. The following briefly describes these cycles and makes clear the distinction between them and the dual fluid cycle engine.